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      <title>倒排索引原理 - 交互式测验</title>
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      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>倒排索引原理 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
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      <script>
        const quizData = [
  {
    "question": "根据文档，倒排索引的核心思想是什么？",
    "options": [
      "将文档内容进行压缩，以节省存储空间。",
      "按照文档的ID顺序，存储每个文档包含的所有关键词。",
      "建立一种从“词项”到“包含该词项的文档列表”的映射关系。",
      "为每个文档创建一个唯一的哈希值，用于快速比较。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "倒排索引的核心在于“反转”了传统的“文档->词项”关系。它以关键词（词项）为索引，直接映射到包含这些关键词的文档列表，从而极大地加快了根据关键词查找文档的速度。传统索引是从文档到词项的映射。",
    "source": "文档中「排索引的概念」部分",
    "hint": "文档中提到，倒排索引将文档中的内容与其所在位置的映射关系“反转”，思考一下这种“反转”指的是什么。"
  },
  {
    "question": "倒排索引的基本结构由哪两个主要部分组成？",
    "options": [
      "文档预处理器和分词器",
      "词项词典 (Lexicon) 和倒排列表 (Inverted List)",
      "查询解析器和结果排序模块",
      "主索引和增量索引"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档明确指出，倒排索引的基本结构由两部分组成：1. 词项词典（Lexicon），用于存储所有词项并快速定位到其对应的倒排列表；2. 倒排列表（Inverted List），记录了每个词项出现在哪些文档中以及相关的位置信息。",
    "source": "文档中「倒排索引的结构」部分",
    "hint": "在索引结构图中，可以看到索引被分为了记录所有词项的部分和记录每个词项对应文档列表的部分。"
  },
  {
    "question": "在构建倒排索引的过程中，“词项标准化 (Normalization)” 阶段的主要目的是什么？",
    "options": [
      "将文档文本切分成独立的词项（token）。",
      "移除文档中的HTML标签和标点符号。",
      "过滤掉如“的”、“是”等常见但无实际意义的停用词。",
      "将词项的不同形式（如 'running', 'ran'）统一转换为其基本形式（如 'run'）。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "词项标准化的目标是消除词项的形态差异，提高索引的一致性。例如，通过词干提取（stemming）或词形还原（lemmatization），可以将不同时态、单复数的单词归一化为其词根或标准形式，这样用户搜索'run'时，也能找到包含'running'的文档。",
    "source": "文档中「倒排索引的构建过程」部分",
    "hint": "这一步骤旨在“消除词项的差异性，提高索引的一致性和准确性”，想想看'running'和'ran'在搜索时应该被如何对待。"
  },
  {
    "question": "当用户执行一个布尔查询 “A AND B” 时，搜索引擎最可能如何利用倒排索引？",
    "options": [
      "将词项A和词项B的倒排列表进行并集操作。",
      "先找到所有包含词项A的文档，然后逐一扫描这些文档是否包含词项B。",
      "将词项A和词项B的倒排列表（文档ID列表）进行交集操作。",
      "随机选择一个词项的倒排列表作为最终结果。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "对于AND操作，系统需要找到同时包含所有关键词的文档。最高效的方法是分别获取每个关键词的倒排列表（即文档ID列表），然后对这些列表求交集。最终得到的交集就是同时包含所有关键词的文档ID集合。",
    "source": "文档中「倒排索引的查询原理」部分",
    "hint": "AND逻辑运算符要求所有条件都必须满足，思考一下在两个文档ID集合中，如何找到同时存在于两个集合中的元素。"
  },
  {
    "question": "与持久化存储相比，将倒排索引完全存储在内存中的一个显著缺点是什么？",
    "options": [
      "查询速度更慢，因为需要进行复杂的内存寻址。",
      "索引的实时更新变得更加困难和复杂。",
      "受限于服务器物理内存大小，且在服务器故障时有数据丢失的风险。",
      "无法支持复杂的查询操作，如短语查询。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "内存虽然提供了极快的读写速度，但其容量是有限的，这限制了能够处理的索引规模。此外，内存是易失性存储，一旦服务器断电或发生故障，未持久化的数据将会丢失，这是内存存储的主要风险。",
    "source": "文档中「倒排索引的存储和持久化」部分",
    "hint": "思考一下内存（RAM）和硬盘（Disk）在容量和数据安全性上的根本区别。"
  },
  {
    "question": "为了精确地处理“短语查询”（例如，查找“分布式系统”这个完整的短语），倒排列表除了需要存储文档ID外，还必须包含什么额外信息？",
    "options": [
      "词项在文档中出现的频率 (Term Frequency)。",
      "词项在文档中的具体位置信息 (Position Information)。",
      "文档的最后修改时间。",
      "词项的权重分数 (Score)。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "短语查询要求关键词必须按照指定的顺序连续出现。为了验证这一点，系统不仅要知道一个词出现在哪个文档里（文档ID），还必须知道它在该文档中的具体位置（例如，是第5个词还是第10个词）。通过比较位置信息，才能判断它们是否构成一个短语。",
    "source": "文档中「倒排索引的查询原理」部分",
    "hint": "要判断“分布式”和“系统”这两个词是否“按照指定顺序连续出现”，仅仅知道它们都在同一个文档里是不够的。"
  },
  {
    "question": "在高并发场景下，为了在允许多个线程同时读取索引的同时保证写入操作的原子性和一致性，文档中提到的一种常用机制是什么？",
    "options": [
      "乐观并发控制 (Optimistic Concurrency Control)",
      "缓存机制 (Caching Mechanism)",
      "读写锁机制 (Read-Write Lock)",
      "分段锁机制 (Segment Lock)"
    ],
    "correctAnswerIndex": 2,
    "explanation": "读写锁是一种非常适合“读多写少”场景的并发控制机制。它允许多个读操作并发执行，互不阻塞，从而提高读取性能。但当有写操作时，它会阻塞其他所有读写操作，确保写入的原子性，防止数据冲突。",
    "source": "文档中「倒排索引的并发和分布式处理」部分",
    "hint": "该机制的核心是区分操作类型：一种操作是共享的，允许多个并发；另一种是独占的，一次只允许一个。"
  }
];
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            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
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            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

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                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
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                '<div class="score-card">' +
                '<h3>正确率</h3>' +
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                '<div class="score-card">' +
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                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  